Pariah

6k before wednesday.

https://www.youtube.com/watch?v=O2dRzoHEQ-c
https://www.youtube.com/watch?v=L-_eV7zdCeg

the rating in Korea doesn't seem to be very good, such a shame because this is easily one of the best drama I've watched

You mean this? https://www.youtube.com/watch?v=4Pps24AdIoI

eunuch Hong is definitely ninth dan and he's probably the most powerful character outside of the grandmasters, Wu Zhu and Fan Xian himself(at near end of the novel)

The emperor is indeed a grand master. He's that secret grand master inside the palace that most people assume it's eunuch Hong.
The grand masters are 1. Ku He of Beiqi 2. Ye Liuyun of Jindou 3. Sigu Jian of Dongyi. 4. The Emperor of Qing.

It's Thai greeting and I believe it's what the bride do in a Thai wedding.

Edit the tags a bit. The ML is a prince, albeit a minor one, as Than Chai is the style of Mom Chao (HSH Prince)